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A Highly Efficient Friedel–Crafts Reaction of 3‐Hydroxyoxindoles and Aromatic Compounds to 3,3‐Diaryl and 3‐Alkyl‐3‐aryloxindoles Catalyzed by Hg(ClO 4 ) 2 ⋅3 H 2 O
Author(s) -
Zhou Feng,
Cao ZhongYan,
Zhang Jing,
Yang HaiBo,
Zhou Jian
Publication year - 2012
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201100773
Subject(s) - friedel–crafts reaction , catalysis , chemistry , carbocation , alkyl , aryl , nucleophile , medicinal chemistry , perchlorate , organic chemistry , ion
We report a highly efficient Friedel–Crafts reaction of 3‐alkyl or 3‐aryl 3‐hydroxyoxindoles with a variety of aromatic and heteroaromatic compounds to unsymmetrical 3,3‐diaryloxindoles or 3‐alkyl‐3‐aryloxindoles, which are interesting medicinal targets and useful building blocks for the synthesis of natural products. Hg(ClO 4 ) 2 ⋅ 3 H 2 O was identified as a powerful catalyst for this reaction, and is significantly more efficient than other screened metal perchlorate hydrates and Brønsted acids such as HOTf and HClO 4 . The high catalytic property of Hg(ClO 4 ) 2 ⋅ 3 H 2 O originates from the unprecedented dual activation effects of aromatic mercuration , which could generate a strong protic acid to facilitate the generation of a carbocation at the C3‐position of oxindoles and simultaneously form the more reactive nucleophilic reaction partner.